Method and apparatus for cutting underwater structures

ABSTRACT

A method for the cutting of underwater structures below the level of the sea bottom on which they are installed, comprising the following phases: determination of the ideal plane of cutting, having considered the characteristic features of the structure ( 30 ) i.e. its morphology and its positioning on the bottom ( 20 ), the shape and consistency of the bottom ( 20 ) itself, and the depth below the level of the bottom ( 20 ) at which the cut must be effected; positioning and anchoring of the cutting means ( 1, 2, 3, 4; 5, 2, 3, 4; 7, 8, 2, 3, 4; 9, 2, 3, 4 ) in proximity of the cutting area; obtainment of at least one perforation or boring ( 21 ) in proximity of the structure ( 30 ) through the bottom ( 20 ) at least up to the predetermined level for the cutting of the structure, along a direction parallel to the cutting direction and preferably lying on the cutting plane; and introduction of the cutting means ( 3, 4 ) inside said perforation or boring ( 21 ) and cutting of the structure ( 30 ); and an apparatus for carrying out said method.

DESCRIPTION

[0001] The present invention relates to a method and an apparatus forcutting underwater structures.

[0002] The cutting of submerged structures, with the purpose of removaland/or substitution of same, is presently effected by adopting differentmethods and by utilising apparatus of different nature.

[0003] There are known devices for the cutting of submerged structureswhich operate with fixed blades, such as the one described for examplein the document U.S. Pat. No. 3,056,267, or provided with several rotaryblades co-ordinated in their action as in the document U.S. Pat. No.4,180,047. Both apparatus however present the disadvantage of operatingonly on the emerging and free end of the submerged structure.

[0004] In the document EP-B-0 540 834, owned by the same applicant,there are described a method and a device for cutting underwaterstructures which make use of a diamond cable as cutting means; thedevice permits the cutting of the underwater structure at any levelcomprised between the bottom end and the surface.

[0005] Presently, the new provisions which are in force practicallyeverywhere, and which are extremely more severe as for what concerns theenvironmental impact, require that the cutting of the submergedstructures cannot be effected by leaving the residual stump of thestructure emerging from the (sea) bottom, but instead by effecting thecut below the level of the bottom itself. Under these conditions, byutilising the presently available means, it results necessary to removea relevant quantity of sea bottom around the base of the structure to becut. This further operation, besides being costly, is frequentlydamaging as for what concerns the environment, which on the contrarythis type of “underground” cutting would tend to safeguard.

[0006] Object of the present invention is therefore to provide for amethod for cutting the underwater structures which permits to effect thesaid cutting below the level of the bottom and with a minimumexpenditure of means and of energies, and with an impact with respect tothe marine environment which is as limited as possible, obtained with aminimum removal of material from the bottom.

[0007] A further object of the present invention Is to provide anapparatus adapted for carrying out the thus conceived cutting method.

[0008] Object of the present invention is therefore a method for thecutting of underwater structures below the level of the sea bottom onwhich they are installed, comprising the following phases:

[0009] determination of the ideal plane of cutting, having consideredthe characteristic features of the structure i.e. its morphology and itspositioning on the bottom, the shape and consistency of the bottomitself, and the depth below the level of the bottom at which the cutmust be effected;

[0010] positioning and anchoring of the cutting means in proximity ofthe cutting area;

[0011] obtainment of at least one perforation or boring in proximity ofthe structure through the bottom at least up to the predetermined levelfor the cutting of the structure, along a direction parallel to thecutting direction and preferably lying on the cutting plane;

[0012] introduction of the cutting means inside said perforation orboring and cutting of the structure.

[0013] According to a preferred embodiment of the method according tothe invention, there are obtained preferably two perforations or boringshaving parallel axes, and arranged in such a manner that the structureto be cut results to be placed between the said perforations or borings.

[0014] The positioning and the anchoring of the cutting means iseffected both on the bottom in proximity of the structure to be cut, andonto the structure itself.

[0015] A further object of the invention is an apparatus for carryingout the method according to the invention, comprising means forperforation or boring, means for cutting which comprise a cutting frameand a movable cutting unit, means for positioning said perforation meansand said cutting means, and anchoring means. Advantageously saidperforation means and said cutting frame are associated, and the meansfor the positioning and anchoring of the perforation means and of thecutting means are the same.

[0016] Further advantages and characteristic features of the presentinvention will appear evident from the following detailed description ofsome preferred embodiments of same, made as non-limiting example withreference to the annexed sheets of drawings, in which:

[0017]FIG. 1 is a perspective view of a first embodiment of theapparatus for carrying out the method according to the invention, duringits positioning in proximity of a submerged structure to be cut;

[0018] FIGS. 2 to 4 show in succession the operative steps of the methodaccording to the present invention;

[0019]FIG. 5 is a side elevation view with parts in section of a secondembodiment of the apparatus according to the invention;

[0020]FIG. 6 is a transverse section view along line VI-VI of FIG. 5;

[0021]FIG. 7 shows the positioning in proximity of the structure to becut of a third embodiment of the apparatus according to the invention;

[0022]FIG. 8 shows the operation of the apparatus shown in FIG. 7;

[0023]FIG. 9 is a section view along line IX-IX of FIG. 8;

[0024]FIG. 10 shows the operation of a further embodiment of theapparatus according to the present invention; and

[0025]FIG. 11 is a perspective view of the means for supporting theapparatus according to the invention shown in FIG. 10.

[0026] In FIG. 1 there is shown the apparatus intended to perform themethod according to the present invention; reference numeral 1designates the supporting base of the apparatus, having a substantiallyrectangular shape, which is provided in proximity of each of its cornerson the upper face with four lugs 101 to which there are secured thelifting rods or cables 11 which connect the base 1 to the haulage cable10. The base 1 is further provided with means for anchoring to thebottom 20 in proximity of the structure 30 to be cut; said anchoringmeans comprise claws 201 which are swingable with respect to the ears301 projecting out of the base 1 and connected to pairs of hydraulicjacks 401, provided with opposed stems 411.

[0027] To the base 1 there is connected the plate 2, to the lugs 112 ofwhich there are hinged, at one of their ends, the two guides 302, bymeans of the flaps 322 projecting out of same; in proximity of the otherend the said guides 302 are instead connected through the flaps 312 tothe articulated arm 202, 212, hinged on its turn to the lugs 222 of theplate 2. The two ends of the branches 202, 212 of the articulated armwhich are connected between each other, are connected to the stem 122 ofthe jack 102 which by its other end is swingably connected to the lug112. The two guides 302 are united between each other by means of thetraverse bar 402.

[0028] Onto the guides 302 there are arranged two tubular members 3which are longitudinally slidable thanks to the slides 403 integral tosaid members 3, mounted in overhanging manner in the same slides 403. Atthe end of said tubular members 3 directed towards the end of the guides302 directly hinged to the plate 2 there are arranged the means forboring the bottom, comprising the boring or cutting heads 303 while atthe opposite end of said tubular members 3 there are arranged two ducts203 for discharging the material removed during the boring of thebottom. On each one of the tubular members 3 there is obtained, facingthe other tubular member, a longitudinal slot 103; between the twoslots, of which only one is visible in the Figure, there is arranged thecutting tool, comprising the diamond cable 4, movable within the saidtubular members 3 by means of devices which will be after illustratedand described.

[0029] In FIG. 2 the apparatus according to the invention has beenplaced on the bottom 20 next to the structure to be cut 30, and theclaws 201, under the action of the jacks 401, have been driven into thebottom itself, thus anchoring the base 1 and setting the apparatus readyfor subsequent operations.

[0030] In FIG. 3 the jacks 102 have been actuated so as to lift thearticulated arms 202, 212 which act on the guides 302. Consequently thesaid guides 302 and also the tubular members 3 arranged onto same, havebeen suitably inclined with respect to the plane of the bottom; the saidinclination is selected according to the ideal cutting plane which hasbeen established for the cutting of the structure 30, and which dependssubstantially from the characteristic features of the structure itself,such as position, section and material, from the characteristic featuresof the bottom and from the depth at which the cut must be effected belowthe level of the bottom itself. As soon as the desired inclination hasbeen reached, the tubular members are displaced by means of the slides403 along the guides 302, and the boring heads 303 penetrate into thebottom 20 thus forming two perforations 21. Said perforations areobtained parallely to the ideal cutting direction of the cutting tool 4,and in such a manner that the structure is comprised between the saidperforations. The material removed by the boring heads 303, is suitablyconveyed along the tubular members 3 and discharged onto the bottomthanks to the discharge ducts 203.

[0031] In FIG. 4 the perforation phase of the bottom has been completed,and the boring heads have reached and passed beyond the level at whichthe cut must be effected. At this point, the cutting means are actuatedand the cutting tool 4, that is the diamond cable, is caused tointerfere firstly with the portion of bottom comprised between the twoperforations 21 and after with the structure 30, thus originating thecut 31. The cutting means can thereafter be retracted up to the positionshown in FIG. 3 and the boring heads are extracted out of the respectiveperforations 21, by causing the slides 403 to slide in oppositedirection on the guides 302; the portion of the submerged structure 30which is located above the cut 31, can be conveniently grasped andremoved.

[0032] From what above said it appears evident that the method accordingto the present invention obviates several inconveniences which wereencountered up to the present date at the moment in which there shouldbe effected the cutting of submerged structures below the level of thebottom on which said structures are positioned. In fact, instead of theample excavations around the structure which are necessary up to thepresent date in order to reach the desired depth, the cutting means areguided inside perforations which remove a minimum portion of the bottom,thus remarkably limiting the environmental impact of the operation, andincreasing remarkably the simplicity and rapidity of the action.

[0033] In FIG. 5 there is shown a second embodiment of the apparatusaccording to the invention; identical reference numerals designateidentical parts. In this case the base 1 is mounted on sliding shoes 5,provided with propellers 105 transversely oriented with respect to saidsliding shoes and with propellers 205 axially oriented. The propellers105, 205 are mounted on respective supports 115, 215.

[0034] As it can be noted from the Figure, the boring head 303 at theend of the tubular member 3 is keyed onto the shaft 323 of a speedreducer 313; its side wall which has a substantially conicaldevelopment, according to this embodiment is formed by the blades 343which are angularly equispaced. In the portion of the tubular memberimmediately downstream of said speed reducer 313, the wall 503subdivides the interior of said member 3 into the duct 523 for thedischarge of the material removed by the boring head 303 and into theportion 513 inside which there are arranged the cutting means, whichcommunicates with the exterior through the slot 103 in which thereslides the cutting tool 4. At the opposite end of the tubular member 3,on the discharge duct 523 there is positioned an aspirator 213, whichdischarges the debris into the discharge duct 203.

[0035] The tubular member 3 is mounted overhanging on the slide 403which moves along the guide 302 thanks to the speed reducer 423 integralwith said slide and which carries on its shaft 423 a pinion 433 whichco-operates with the rack 332 arranged on the side wall of the guide302.

[0036]FIG. 6 is a section view along line VI-VI of FIG. 5; at theinterior of the tubular member there are arranged the cutting meanscomprising the cable 4 preferably of the diamond type, which is arrangedon the pulley 104, keyed onto the shaft 114 which is inserted in thecarriage 204. One end of the shaft 114 is provided with a bevel pinion124 which engages the bevel pinion 414 of the speed reducer 404 arrangedon the carriage 204. The carriage 204 is provided with two sliding shoes214 which co-operate with the guides 304 connected with the wall 503which divides the tubular member 3 into the portion 513 and into theduct 523; to the said wall 503 there is also applied the pipe 333 whichcarries the feeding fluid to the speed reducer 313 of the boring head302 (see FIG. 5). On the carriage 204 there is overhangingly connectedthe speed reducer 504 on the shaft 524 of which there is keyed a pinion514 which engages the rack 533 arranged on the wall 503. The speedreducers 404 and 504 are fed through the pipes 424 and 534 carried bythe supporting member 603 movable along the guide 613 formed on theinner wall of the tubular member 3.

[0037] The operation of the apparatus adapted to carry out the methodaccording to the invention will appear evident from the following. Thepositioning of the apparatus on the bottom 30 can be controlled from thesurface, as shown in FIG. 1, by means of the haulage cable 10, or theapparatus can be positioned with respect to the structure to be cut byusing means placed directly on the apparatus itself, as in the case ofthe propellers 105, 205 shown in the embodiment of FIG. 5. In bothcases, after the positioning and the anchorage of the apparatus, theguides 302 are oriented with respect to the structure to be cut thanksto the jacks 102 which act onto the articulated arms 202, 212 so as toposition them on the ideal plane of cutting of the said structure.

[0038] Subsequently the speed reducers 413 are actuated to permit theforward movement of the slides 403 which carry the tubular members 3, atthe ends of which there are mounted the boring heads 303 which aredriven in rotation by the speed reducers 313. As the boring headspenetrate into the bottom 30, the produced debris are conveyed into theducts 523 provided at the interior of the tubular members 3 and underthe action of the aspirators 213 are expelled through the dischargeducts 203.

[0039] When the boring heads have reached the suitable depth withrespect to the structure to be cut, the perforation is interrupted, andthere is actuated the speed reducer 504 which is mounted on the carriage204 which carries the diamond cable 4, together with the speed reducerwhich drives the pulley 104 on which there is arranged the cable 4itself. The cutting means move forward along the tubular members 3,until they meet first the bottom 2 b and then the structure 30, intowhich there is made the cut 31. At this point also the cutting means canbe stopped and subsequently retracted by abandoning, if the case, thecable; afterwards the tubular members 3 will be retracted and there willbe recovered the structure 30 thus cut.

[0040] In FIG. 7 there is shown another embodiment of the apparatusaccording to the present invention; identical reference numeralsdesignate identical parts. In the illustrated case the already describedplate 2 is connected to the support 7 which forms together with themovable plane 407 and the levers 107 and 207, which are hinged to both,an articulated parallelogram. To the lever 207 there is connected in aswingable manner the stem of the jack 307 which by its other end ishinged to the plane 407. The said plane 407 is hinged by one end to thelug 408 of the anchoring frame 8, while at the other end it is coupledto the stem 318 of the jack 308 connected to the said anchoring frame 8.The anchoring frame 8 is provided with two anchoring clamps 108,intended to seize the structure 30. The apparatus is connected to thehaulage cable 40 by means of the lifting rods or cables 41 which areconnected to the slots 508 and 507.

[0041] In FIG. 8 the apparatus according to the embodiment of FIG. 7 isshown at the end of the cutting phase of the structure, with the tubularmembers inside the perforations 21 and the cutting tool 4 which hastraversed the structure 30 itself. As it can be appreciated, in thiscase the anchoring of the apparatus is performed directly on thestructure 30 itself, and the positioning of the boring means and of thecutting means is obtained thanks to the three, different possibilitiesof adjustment consented by the articulated parallelogram of the support7, by the jack 308 of the movable plane 407 and by the articulated arm202, 212 which, in co-operation with the jack 102, operates on the otherhand in a manner analogous to what previously described with referenceto the other embodiments of the apparatus according to the presentinvention.

[0042] In FIG. 9 there is shown, in section along line IX-IX of FIG. 8,a clamping jaw 108. Onto the two fixed arms 108 there are mounted,swingable on the pins 138, a pair of rocking levers 118, each of whichis provided at one end with a blocking element 128, which is alsoswingable with respect to the lever 118, and at its other end hinged tothe stem 158 of the jack 148, on its turn swingably connected to theanchoring frame 8. Between the two jacks 148 connected to the arms thereis arranged a jack 208 on the stem of which there is positioned ablocking element 228 which consents the seizing of the structure 30 andthe centring with respect to same.

[0043] The advantages deriving from this embodiment are evident; in thefirst place it is not affected during its operation by any influenceconnected to the features of the bottom and to its regularity, since theonly part which comes Into contact with the bottom is only the one whichpenetrates the bottom itself, that is the tubular members 3, the boringheads 303 and the cutting tool 4. In the second place the structure 30,after the cutting, remains connected to the support of the apparatus,that is to its anchoring means represented by the clamping jaws 108, andit can be therefore better controlled during its removal.

[0044] In FIG. 10 there is shown another embodiment of the apparatusaccording to the present invention; the plate 2 is mounted onto a base409 connected to the upright of a stand frame 9 which comprises adiagonal beam 209 and a traverse beam 309; at the end of the diagonalbeam 209 connected to the traverse beam 309 as well as at the end of theupright 109 connected to the traverse beam there is provided a foot 219.All the feet 219 are provided with perforation means 509 and withexpansion inserts 609. The perforating means 509 generate the bores 22inside which the foot 219 and the end of the upright are inserted, andthe expansion inserts 609 perform the locking in place. As it can beseen in FIG. 11, the stand frame 9 comprises two uprights 109, twodiagonal beams 209 and two traverse beams 309, facing each other andconnected by the transverse bars 119 and 319.

[0045] The support of the apparatus of the invention, conceived in thismanner, considerably reduces the space required for the positioning ofthe apparatus in proximity of the structure to be cut, and therefore canbe useful in those cases in which the bottom in its proximity presentsirregularities, or a flat bottom portion of limited extension. Moreoverthe anchoring system appears to be particularly quick and efficacious,capable of adapting itself to extremely difficult ambient situations.

[0046] The method according to the present invention and the apparatusfor carrying out said method consent therefore to reach remarkableresults from the point of view of the rapidity of operation, of theeffectiveness and of the environmental impact which is extremelylimited.

1. A method for the cutting of underwater structures below the level ofthe sea bottom on which they are installed, comprising the followingphases: determination of an ideal plane of cutting, having consideredthe characteristic features of the structure (30) i.e. its morphologyand its positioning on the bottom (20), the shape and consistency of thebottom (20) itself, and the depth below the level of the bottom (20) atwhich the cut must be effected; positioning and anchoring of the cuttingmeans (1, 2, 3, 4; 5, 2, 3, 4; 7, 8, 2, 3, 4; 9, 2, 3, 4) in proximityof the cutting area; obtainment of at least one perforation or boring(21) in proximity of the structure (30) through the bottom (20) at leastup to the predetermined level for the cutting of the structure, along adirection parallel to the cutting direction and preferably lying on thecutting plane; introduction of the cutting means (3, 4) inside saidperforation or boring (21) and cutting of the structure (30).
 2. Amethod according to claim 1, in which there are obtained twoperforations or borings (21) having parallel axes, and arranged in sucha manner that the structure to be cut (30) results to be placed betweenthe said perforations or borings (21).
 3. A method according to claim 1,in which the positioning and the anchoring of the cutting means (1, 2,3, 4; 5, 2, 3, 4; 9, 2, 3, 4) is effected on the bottom (20) inproximity of the structure (30) to be cut.
 4. A method according toclaim 1, in which the positioning and anchoring of the cutting means (7,8, 2, 3, 4) is effected onto the same structure (30) to be cut.
 5. Anapparatus for carrying out the method for the cutting of underwaterstructures below the level of the sea bottom, comprising the phases of:(a) determination of an ideal plane of cutting, having considered thecharacteristic features of the structure; (b) positioning and anchoringof the cutting means in proximity of the cutting area; (c) obtainment ofat least one perforation or boring in proximity of the structure throughthe bottom at least up to the predetermined level for the cutting of thestructure, along a direction parallel to the cutting direction andpreferably lying on the cutting plane; (d) introduction of the cuttingmeans inside said perforation or boring and cutting of the structure,characterised by the fact of comprising means for perforation or boring(303), means for cutting which comprise a cutting frame (2, 3, 304, 533)and one movable cutting unit (204, 504, 404, 4), means for thepositioning (302, 202, 212, 102, 122; 307, 207, 308, 407) of saidperforation means (2, 3, 303) and of the said cutting means (2, 3, 304,533, 204, 504, 404, 4) and anchoring means (201, 401; 108, 509, 609). 6.An apparatus according to claim 5, in which the said means forperforating or boring (303) are associated with the said cutting frame(2, 302, 3) and the positioning means (302, 202, 212, 102, 122; 307,207, 308, 407) of the cutting means and of the perforation means are thesame.
 7. An apparatus according to claim 6, in which said cutting framecomprises a plate (2) onto which there are hinged (322) two guides (302)parallel and connected between each other, provided with adjustmentmeans (102, 122, 202, 212) of the inclination with respect to the saidplate (2), on said guides (302) there being arranged longitudinallymovable the said perforation means (3, 303) and the said movable cuttingunit (204, 504, 404, 4), said plate (2) being connected with supportingmeans (1; 7, 8; 5; 9).
 8. An apparatus according to claim 7, in which onsaid guides (302) there are arranged two tubular members (3) mounted ina cantilever fashion each one on a slide (403) movable on said guides(302) under the action of driving means (413, 433, 332), saidperforation means (303) being arranged at one end of said tubularmembers (3) and at the interior of said tubular members there beinghoused the said movable cutting unit (204, 504, 404, 4), the cuttingtool (4) being arranged transversely with respect to the said tubularmeans, and passed through two longitudinal slots (103) facing each otherand obtained therein.
 9. An apparatus according to claim 8, in which thesaid perforation means comprise boring heads (303) formed by a pluralityof blades (343) arranged on a substantially conical surface andangularly equispaced, provided with driving means (313, 323).
 10. Anapparatus according to claim 8, in which said tubular members (3)comprise each at its interior a discharge duct (523) of the materialremoved by the said perforation means (303), and a space (513) forhousing the said movable cutting unit (204, 504, 404, 4).
 11. Anapparatus according to claim 8 in which the said movable cutting unitcomprises a carriage 204 arranged inside each of the said tubularmembers (3), movable on guides (304) suitably positioned by drivingmeans (504, 533), on which there is arranged at least one pulley (104)provided with driving means (404), which carries a closed loop cable,preferably a diamond cable.
 12. An apparatus according to claim 7, inwhich the said supporting means comprise a base (1) substantially flatprovided with means (201, 401) for anchoring to the bottom.
 13. Anapparatus according to claim 12 in which the anchoring is effected dueto gravity.
 14. An apparatus according to claim 12, in which the saidanchoring means comprise two or more claws (201) hinged to the said base(1) and provided with actuating means (401).
 15. An apparatus accordingto claim 12, in which the said anchoring means comprise two or more feet(219) provided with perforation means (509) and with expansion inserts(609).
 16. An apparatus according to claim 12, in which the said base(1) is mounted on sliding shoes (5).
 17. An apparatus according to claim12, in which the said supporting means are provided with means formoving the apparatus (105, 205).
 18. An apparatus according to claim 17,in which said means for moving comprise at least one propeller (105,205).
 19. An apparatus according to claim 7, in which the saidsupporting means comprise a stand frame (9) substantially formed by twouprights (109), two diagonal beams (209) and two transverse beams (309)respectively parallel to each other, connected by two transverse beams(119) at the said diagonal beams (209), said plate (2) being positionedonto said uprights (109), said stand frame (9) being provided with fourfeet (219) provided with anchoring means (509, 609).
 20. An apparatusaccording to claim 7, in which the said plate (2) is connected, throughadjustable connecting means (7, 407, 307, 207) to an anchoring frame (8)to the structure to be cut (30), provided with means (108) for clampingthe structure (30) to be cut.